How do I keep bad spirits from coming through, if that is even possible?

Practically speaking the best way to keep bad spirits from coming through is not to invite them into your house in the first place. By this I mean invite directly through use of popular spirit medium tools such as the ouija board but also indirectly by promoting an atmosphere of negativity and conflict in the house that a mischievious or malicious spirit may be attracted to. 

The type of spirits you would not want in your home will be compelled towards households of disharmony, houses with arguing and unhappiness. So keeping the communication channels open and not letting negativity foster is a great first step.

Presuming you’re not taking any steps to actively invite spirits into your home (and if you are, stop it, there’s your answer) there are a couple of extra precautions you can take. One of the most common is to seal the entrances and exits to your home with blessed water (remembering to include the windows). Blessed water is simply water that you have asked your deity/deities to bless. I tend to use water that has sat in the rays of the full moon for a night but if this isn’t possible tap water will be a satisfactory substitute. Once blessed, sprinkle the water round your entrances and state firmly (speaking aloud) that you invite nothing into your home that bears you ill will. Repeat this process and vocalisation for each entrance.

You can also try sprinkling salt across your threshold and walking the parameters of your home with an incense burned for protective purposes (I favour cedarwood for this).

Image http://www.deviantart.com/art/Ghost-Bride-72597205

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